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If a fair coin is tossed twice… (Class 10 Maths 2023, Q24)

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MathsCBSE Class 10 · Standard · Board exam 2023, set 30/4/1 · 2 marks · Very short answer

CBSE Class 10 Mathematics Standard 2023: question 24

Set in the CBSE Class 10 board exam of 2023, paper 30/4/1, section B, question 24, for 2 marks. Try it first; the hints and our step-by-step solution are below.

Q24 · 2 marks · Very short answerProbability

If a fair coin is tossed twice, find the probability of getting 'atmost one head'.

Source: official question paper from cbse.gov.in (PDF). See it in the full 2023 board paper, set 30/4/1.

Hints

Open one hint at a time and try again before the next.

Hint 1

Write down every possible result of two tosses.

Hint 2

'At most one head' allows zero heads as well as exactly one head. Which outcomes have no more than one H?

Step-by-step solution

Each step shows the marks it earns, as an examiner would award them. Checked by an independent re-solve from the question paper.

  1. When a fair coin is tossed twice, the sample space is . So the total number of outcomes is .

    ½ mark

  2. 'At most one head' means 0 heads or 1 head. The favourable outcomes are , so there are of them.

    ½ mark

  3. 1 mark

Answer:

Where the marks are

  • Lists all 4 outcomes HH, HT, TH, TT (½ mark)
  • Identifies the 3 favourable outcomes HT, TH, TT (½ mark)
  • Gets the probability (1 mark)

Revise the chapter

  • Chapter: Probability (notes, formulas, where marks are lost and every past question)
Practise this chapterBoard-style questions from Probability, one at a time, marked against the answer key and marking points.Back to the full paper2023 board paper, set 30/4/1 (Standard): every question, by section.

The question is transcribed from the official paper; figures are described in words. The solution, hints and chapter tag are ours. Spotted an error? Write tosupport@questionbuddy.in.